Key operated locks



- Filed Aug. 28, 1964 May 23, 1967 L. J. HILL 3,320,781

KEY OPERATED LOCKS 3 Sheets-Sheet 1 INVENTOR. LEW/"s H/Zz.

May 23, 1967 L. J. HILL 3,320,781

KEY OPERATED LOCKS Filed Aug. 28, 1964 3 heets-Sheet 2 l NVEN TOR. Lew/"s 1, H/ZL y 1967 L. J. HILL 3,320,781

KEY OPERATED LOCKS Filed Aug. 28, 1964 3 heets-Sheet 3 INVENTOR. Ls-wis L/a H/LL A rrap/w-rs Patented May 23, 1957 3,s2a;.1s1 KEY OPERATED LOCKS Lewis J. Hill, 1121 Linwood, Oklahoma (Iity, Okla. 731436 Filed Aug. 225, 1964, Sea. N0. 33A93 7 (Ilaims. (Ql. Wi -3S4) This application is a continuation-in-part of my copending application for Key Operated Lock, Ser. No. 352,740, filed Mar. 18, 1964, and now abandoned.

This invention relates generally to improved key operated locks. More particularly, but not by way of limitation, this invention relates to an improved key operated lock incorporating mechanism adapted to permit the lock to be easily and rapidly changed for operation by different keys.

In many situations in which locks are used, it would be highly desirable to be able to immediately change the lock, or at least rearrange the lock mechanism so that a different key is required to operate the lock. For example, in apartment buildings, hotels, or motels, a guest or renter may inadvertently or intentionally leave and retain the key to open the lock securing the door. A subsequent occupant of the room cannot be secure when a key has been retained in this Way. Also, the establishment may be liable for missing property in the event they do not promptly change the lock.

Locks that can be easily changed are also needed by various types of businesses wherein several employees are in possession of keys to fit the locks. The need arises when an employee is discharged or quits, but retains possession of the key. Also, changeable locks are very beneficial when one employee loses his key, thus placing the security of the locked area in doubt.

Changeable locks are not new, per se. However, the previously constructed locks of this type have not proved to be entirely satisfactory. In general, the locks are extremely complex and, due to their complexity, have been too expensive to be commercally successful. Furthermore, it is not believed that changeable locks constructed in the past have included any satisfactory means for operating such locks by a master key.

One other disadvantage of some of the changeable locks constructed in the past is that they are subject to being unlocked or changed without the use of the proper key.

A lock constructed in accordance with the invention includes a body having a cylindrical bore therein and an elongated plug rotatably mounted in the bore. At least one driver is positioned in an aperture extending radially through the body into the bore. At least one adjustable tumbler is positioned for radial movement in the plug in response to a main key inserted in the lock. The arrangement and construction of the lock provides for cooperation between the drivers, tumblers, plug, and body to prevent relative rotation between the plug and body when the wrong main key, or no key, is inserted in the lock, but permits such rotation upon insertion of the proper main key. Furthermore, the lock is arranged to permit changing the length of the key-following tumblers to permit the use of a different main key without disassembling the lock.

In another aspect, the invention contemplates a lock constructed in accordance with the foregoing, but also including a master key lug on the tumblers. The master key lugs are arranged to be engaged by a master key inserted in the key slot, whereby the same master key will operate the lock regardless of the effective length of tie key following tumblers.

One object of the invention is to provide an improved changeable key operated lock that can be changed for operation by different keys without disassembling the lock.

Another object of the invention is to provide an improved changeable key operated lock that is tamper-proof.

Still another object of the invention is to provide an improved changeable key operated lock that cannot inadvertently be locked during the key changing process.

One other object of the invention is to provide an improved changeable key operated lock that incorporates simple means for changing from one key to the other.

A still further object of the invention is to provide an improved changeable key operated lock that has relatively few moving parts, yet, provides many locking combinations.

An additional object of the invention is to provide an improved changeable key operated lock that can be operated by a main key or a master key and that can be easily and quickly changed for operation with difierent main keys while remaining operable by the same master key. Stated in another way, the lock can be operated by the same master key regardless of changes made to adapt the lock for operation with different main keys.

The foregoing and additional objects and advantages of the invention will become more apparent as the following description is read in conjunction with the accompanying drawings wherein like reference characters denote like parts in all views, and wherein:

FIG. 1 is a front elevation view of a lock constructed in accordance with one embodiment of the invention;

FIG. 2 is a cross-sectional view of the lock of FIG. i. taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged cross-sectional View of a tumbler used in the lock of FIG. 1;

FIG. 4 is a transverse cross-sectional view of the lock, taken along the line 44 of FIG. 2;

FIG. 5 is a transverse cross-sectional view of the lock, taken along the line 55 of FIG. 2;

FIG. 5a is a transverse cross-sectional view similar to FIG. 5, but showing the various parts in a diiferent operating position;

FIG. 6 is a cross-sectional view similiar to FIG. 2, but showing the various parts in the positions they occupy when the wrong key is inserted in the lock;

FIG. 7 is an elevation view of a change key used in conjunction with the lock of FIG. 1;

FIG. 8 is a transverse cross-sectional view taken along the line 88 of FIG. 6, but showing a portion of the operating mechanism rotated; and,

FIG. 9 is a view similar to FIG. 1 but showing an embodiment of the invention as modified for operation with a master key;

FIG. 10 is a cross-sectional view of the embodiment of the lock of FIG. 9, taken along the line lill0 of FIG. 9;

FIG. 11 is an enlarged cross-sectional view of a tumbler used in the embodiment of the lock of FIG. 9; and

FIG. 12 is a cross-sectional View taken along the line 1212 of FIG. 10.

Referring now to the drawings, and to FIG. 1 in particular, shown therein is a lock assembly generally designated by the reference character 10. The lock assembly 10 includes a body 12 which is illustrated as being generally cylindrical in form and is sometimes referred to in the trade as the cylinder. The body 12 has a cylindrical bore 14 extending therethrough and a plurality of apertures 16 which extend transversely through one wall of the body 12 into the cylindrical bore 14, as best shown in FIGS. 2, 6 and 8. An elongated plug 18, which is preferably generally cylindrical, is rotatably mounted in the bore 14. An index mark 20 is provided on the face of the body 12 and an index mark 22 is provided on the face of the plug 18. The purpose of the indices 24) and 22 will be described more fully hereinafter.

As can be seen more clearly in FIG. 2, the body 12 also includes a circumferential flange 24 extending around me end of the body 12. The purpose of the flange 24 is o abut the face of a door or other member (not shown) 11 which the lock 10 is to be installed. The body 12 has in external thread 26 which is provided to secure the lock 11 the door or other member where the lock is to be :sed. An elongated, dovetailed groove or slot 28 extends From one end of the body 12 to the flange 24 and is prolided to accommodate a plate 39 which, when placed in :he slot 28 covers the apertures 16 in the body 12. The iovetailed configuration of the slot 28 may be more clearly seen by reference to FIGS. and 5a. A driver 32 is slidngly positioned in each of the apertures 16 in the body 12. The drivers 32 areconstantly urged toward the plug 18 by a spring 34 which has one end disposed in the driver 52 and the opposite end thereof abutting the elongated plate 38. For reasons which will be subsequently pointed out, the cylindrical bore 14 of the body 12 has a counterbore 36 forming a shoulder 38 in the face thereof.

The plug, which is generally cylindrical in shape to fit within the cylindrical bore 14 of the body 12, has a flange portion 46 providing an inwardly facing shoulder 42 which is adapted to abut the shoulder 38 in the body 12 to prevent movement of the plug 18 toward the rear of the lock. 1%. The opposite end of the plug 18 is suitably arranged at 44 to be attached to a lock cam 46 which serves the dual purpose of preventing the plug 18 from moving toward the forward end of the lock 11), and to actuate a lock bolt (not shown). A key slot 48 extends longitudinally through the plug 18 and is suitably configured to accept a key 50 for operating the lock 10. A plurality of apertures 52 extend transversely through the plug 18 having the lower end thereof'in communication with the key slot 48 and being adapted to register with the apertures 16 in the body 12 when the plug 18 is in the position shown in FIGS. 1 and,2. The plug 18 is also provided with a longitudinal change key passageway 54 that extends generally parallel with the key slot 48 and intersects the apertures 52. The purpose of the change key passageway '54 will be explained more fully hereinafter.

A tumbler, designated generally by reference character 56, is slidingiy disposed in each of the apertures 52 in the plug 18. As may be more clearly seen in FIG. 3, each of the tumblers 56 includes a plunger member 58 having a hollow cylindrical housing 68 which is closed at one end 62 thereof. Slidingly disposed within the interior of the hollow cylindrical housing is an extensible member 64 which has an upper portion 65 providing a plurality of circumferential flanges 66 and a lower portion 68 which, when installed in the lock 10, will contact the key 51 A spring member 76 is provided between the closed end 62 of the hollow cylindrical housing 60-and the upper portion 65 of the extensible member 64 to constantly urge the extensible member 64 away from the closed end 62.

A hollow projection 72 extends outwardly from one side of the plunger member 58 and is adapted to receive an elongated, curved latching member 74 therein. A spring 76 encircles the elongated latching member 74 within the hollow projection 72 and exerts a biasing force on a flange 78 disposed on the elongated latching member 74 near an end 80 thereof. The force of the spring 76 is such that the end 81) of the latching member 74 is urged into engagement with the circumferential flanges 66 on the extensible member 64 to retain the member 64 in a fixed position relative to the plunger member 58. It can be- As illustrated, the lock 10 is provided with five tumblers Each of the plungers 58 has six circumferential flanges 66 on the upper portion 65 of the extensible member 64, providing five operating lengths of each of the tumblers 56. Mathematically, such an arrangement provides five raised to the fifth power combinations or variations in the keys which may be used to operate the lock 10. Obviously, more or less combinations may be pro vided by varying either the number of tumblers or the number of operating lengths provided for the individual tumblers. This will become more clearly apparent from the later description of the operation of the invention.

FIG. 4 is a transverse cross-sectional view of the lock 16 taken along the line 4-4 of FIG. 2, and is provided to illustrate a slot 84 which extends between the key slot 43 and the change key passageway 54. Slidingly mounted within the slot 84 is a retaining member 86 which has one end portion 88 adapted to project into the key slot 48, as shown in FIG. 1, and an opposite end 91 which projects into the change key passageway 54, also as shown in FIG. 1. A suitably configured spring 32 has one end positioned in a hole 94 (shown in dash lines in FIG. 4), and an opposite end in contact with the retaining member 86 to bias the retaining member 86 into the position in which one end protrudes into the key slot 48, as shown in FIG. 1.

FIG. 5 is a transverse cross-sectional view of the lock 10 taken along the line 5-5 of FIG. 2, and is provided to illustrate a plate 36 which is pivotally mounted on a pin 98 within a recess 160 formed in the plug 18. The plate 96 is constructed to close the change key passageway 54 when the lock 10 is in the position illustrated in.FIG. 5. With the lock it} in this position, the plate 96 cannot be moved to a position wherein it does not cover the passageway 54 due to the engagement of a lower portion-102 of the plate 96 with both the inner surface of the cylindrical bore 14 and a surface 184 formed by the recess in the plug 18. FIG. 5 also illustrates the formation of a recess 1196 extending outwardly from the bore 14 into the body 12. The purpose of the recess 106 will be explained in connection with the operation of the lock 10.

A change key 108, suitably configured for use with the embodiment of the lock 10 which. has been described, is illustrated in FIG. 7. As shown, the change key 108 includes a handle portion 114) and a blade portion 112. The blade portion 112 has a notch 114 formed therein near the juncture between the blade portion 112 and the handle portion 110. One edge of the notch 114 has a bevel 116 for purposes that will be explained more fully hereinafter.

FIG. 2 illustrates the various parts of the mechanism of the lock 1th in the positions they occupy when the key 50, which is the proper key to operate the lock 10, is inserted in the key slot 48. In order to ,be able to rotate the plug 18 relative to the body 12, the closed end portion 62 of the tumblers 56and the lower end of the drivers 32 must be arranged along a line which is coincident with the plane extending between the plug 18 and body 12.

FIG. 6 illustrates the various positions of the mechanism of the lock 10 when a key 50a, which has the milled surface thereon of a different configuration from the milled surface of the key 56, is inserted in the key slot 48. As illustrated therein, some of'the drivers 32 extend into both the apertures 16 in the body 12 and the apertures 52 in the plug 18. Also, some of the tumblers 56 extend into both the apertures 16 in the body 12 and the apertures 52 in the plug 18. The result of the extension of the drivers 32 and tumblers 56 into both apertures is to prevent the relative rotation of the plug 18 with respect to the body 12.- Thus it can be seen that only the key 50, having the particular configuration of milled surface as illustrated in FIG. 2, will properly align the tumblers 56 and drivers 32 so that the plug 18 can be rotated relative to the body 12 to operate the lock 1%.

The mechanism of the lock 10 can be readily changed to facilitate operation of the lock with the key 50a. To

change the lock so that it can be operated with the key 50, which is the proper key to operate the lock 16, is inserted in the key slot 48 and the plug 18 rotated relative to the body 12 until the indices 26 and 22 are aligned. With the indices aligned, the plate 96 will be positioned adjacent the recess 106 in the body 12. The change key 168 is then inserted in the change key passageway 54, camming the pivotally mounted plate 96 into the recess 106. It should be pointed out that the recess 106 is so formed that the plate 96 cannot be moved to the position uncovering the change key passageway 54 when the plug 18 is in a locked position, as shown in FIG. 5, or in an entirely unlocked position wherein the key slot 48 would be rotated 90 degrees from that shown in FIG. 5. Thus, the plate 96 prevents anyone who does not have the key 51 from uncovering the change key passageway 54 and altering the position of the mechanism of the lock 10. A so, the lock can be left in the open position (not shown) without danger of alteration because, as previously pointed out, the plate 96 cannot be moved into a position uncovering the change key passageway 54 when the plug 18 is rotated 90 degrees in the body 12 from its position illustrated in FIG. 5.

As the change key 108 is inserted in the change key passageway 54, the blade 112 comes into contact with the curved end portion 82 of the elongated latching member 74, moving the latching member 74 outwardly, as shown in FIG. 8. The outward movement of the elongated latching member 74 moves the end 80 thereof out of engagement with the circumferential flanges 66 on the upper portion 65 of the extensible member 64 of the tumblers 56. After the change key 108 has been inserted and the key 56 removed, the key a is inserted in the key slot 48. So long as the change key 108 remains in the lock 10, the extensible members 64 may be moved relative to the plunger members 58 to change the length of the tumblers 56. As the key 56:: is inserted, the lower portion 68 of the extensible member 64 follows the milled surface of the key 50a. When the key 56a is completely inserted, the change key 108 is removed.

As change key 168 is withdrawn from the change key passageway 54, the latching members '74 are released. The spring 76 drives the latching member 74 inwardly, engaging the end 8t) thereof with the circumferential flanges 66 on the extensible member 64. The extensible member 64 is retained by the latching member '74 in a fixed position relative to the plunger member 58. The plug 18 may then be rotated by the key 50a to the horizontal or vertical position, locking or unlocking the lock 19. The key Sila can then be withdrawn from the key slot 48. The lock 10 is arranged to be operated only by the key 50a.

One important feature of the invention involves the cooperation between the retaining member 86 and the change key 11, 3. As previously described, the retaining member 36 has one end portion 88 which extends into the key slot 48 and another end portion it which extends into the change key passageway 54. During the process of changin the lock 10 from a status permitting operation with the key 56 to a status permitting operation by the key 56a, it is possible to withdraw either the key 51 or the key 59a from the key slot 48. With the latching member '74 released from the extensible member 64 and neither key 50 nor key 56:: in the key slot 48, the extensible member 64 will drop to the bottom of the aperture 52. If the retaining member 86 were not provided, withdrawal of the change key 168 would permit the latching member 74 to move inwardly, engaging the uppermost circumferential flange 66 on the upper portion of the extensible member 64, thereby locking the tumbler 56 in its most extended position and preventing the entrance of any key into the key slot 48. To prevent such an occurrence, the retaining member 86 moves inwardly toward the key slot 48 and the change key passageway 54 upon removal of either key 50 or key 50a from the key slot 48. Such movement brings the end 91} of the retaining member 86 into the notch 114 in the blade portion 112 of the change key 168, thereby preventing removal of the change key 168 until a key has been inserted in the key slot 48 to move the end out of the notch 114. The slight bevel 116 in the notch 114 of the change key 163 has been provided to prevent inadvertent locking of the change key 108 in the change key passageway 54 by the retaining member 86 due to wear on the end 88 or slight variation in manufacturing tolerances. While the bevel 116 is not necessary, it permits the reduction of the tolerances to which the retaining member 86 must be held during manufacture.

In summation, the procedure for changing the lock 10 from a status permitting operation by the key 50 to a status permitting operation by the key Stia is as follows:

1) Insert the key 50 in the key slot 48 and rotate the plug 18 in the body 12 until the indices 26 and 22 are aligned;

(2)- Insert the change key 168 in the change key passageway;

(3) Withdraw the key 56 from the key slot 48;

(4) Insert the key 56a in the key slot 48;

(5) With-draw the change key 108 from the change key passageway 54; and,

(6) Rotate the plug 13 within the body 12 to a position wherein the lock 16 is in either the locked or unlocked position, and withdraw the key 56a from the key slot 48.

FIGS. 9, 10, 11, and 12 illustrate another embodiment of the lock which is designated generally by the reference character 1%. As can be perceived from the figures of the drawing illustrating the new embodiment, only the plug and the tumblers have been modified. Therefore, all other portions of the lock will be designated by the reference characters used in connection wtih the figures of the drawing illustrating the lock 16.

As illustrated'in FIGS. 9, l0, and 11, the lock 10% includes a body which is in all respects identical with the body 12 in the lock 16. Disposed within the bore 14 of the body 12 is a plug 118. The plug 118 is, with only two exceptions, identical to the plug 18 utilized by the lock 19. As clearly shown in FIG. 9, the plug is provided with a key slot 143 which has a different configuration than the key slot 48 of the lock 10. The key slot 148 includes a main key portion 148a and a master key portion 143]). The master key portion 143]) extends longitudinally through the plug 118 and intersects the portion 148a near the lower end of the slot 148. The plug 118 also has a groove 160 formed in the side of each of the apertures 52, which groove 166' extends downwardly through the plug 118 to intersect the master key portion 14811 of the key slot 148. The grooves 160 are provided for reasons which will become more apparent as the description proceeds.

As shown in FIGS. 10 and ll, each of the tumblers 156 is provided with a master key lug 162 which depends from a plunger portion 158 of the tumblers 156. The master key lugs 162 project into the grooves 160 when the tumblers 156 are installed in the apertures 52. The lugs 162 have a shaped lower end 164 arranged to engage a milled edge 166 of a master key which is inserted in the key slot 148 as illustrated in FIGURES l0 and 12.

FIG. 11 illustrates an enlarged cross-sectional view of the structure of one of the tumblers 156. As shown therein, the tumblers 156 include an extensible member 64 which is spring loaded in the plunger portion 158 and a latching mechanism 74 for retaining the extensible member 64 in a desired position. A comparison of FIGS. 3 and 11 demonstrates that the tumbler 156 and the tumbler 56 are identical in all respects with the exception of the provision of the master key lug 162 on the tumbler 156. It should be pointed out that the lug 162, is formed on the exterior of the plunger portion 158 in such a position that the lower portion 68 of the extensible member 64 can be adjusted to any desired position wtihout engaging the master key lug 162.

T o operate the lock 180 wit-h the master key, the master key 150 is inserted in thekey slot 148. As illustrated in FIG. 10, the milled edge 166 of the master key 150 engages the master key lug 162.. When the proper master key 159 is inserted in the key slot 14-3, the upper end of the tumblers 156 will be aligned along the periphery of the plug 118 and will permit the plug 118 to be rotated in the body 12 as shown in FIG. 12. Due to the difference in length of the master key lugs 162, it can be seen that if a master key is inserted in the slot 148 which has a milled edge different from that illustrated in FIG. 10, some of the tumblers 156 will extend above the periphery of the plug 113 into the apertures 16 of the body 12 and some of the drivers 32 may extend into the plug 118, thus, preventing relative rotation between the plug 113 and the body 12..

It is very important to note that the master key arrangement as embodied in the lock 100 has no effect on the operation of the lock by means of the main key 59 as illustrated in FIGS. 2 and 8. Furthermore, since the master key lugs 162 are attached to the 'plungers 158 the change in effective length of the tumblers 155 by repositioning the extensible member 64 does not effect the configuration of master key required to position the tumblers 156 as shown in the FIG, 10. It can be appreciated that a lock constructed. in accordance with the embodiment shown in FIGS. 9-12 incorporates all the features of the lock 10 and in addition provides the benefits of a lock which can be operated by a master key. An additional benefit gained in the embodiment of the lock 100 is that should one or more of the tumblers be inadvertently released, such as by failure of the latching mechanism or member 74, which would prevent the main key 50 from operating the lock, it is still possible to release the lock by means of the master key 150.

From the foregoing it can be seen that a lock constructed in accordance with the invention is tamper-proof. No parts used to change the mechanism of the lock 10 are available on the outside of the lock. Thetool required to change the setting of the lock 10 cannot be inserted unless the proper key has been used and the lock rotated to the position aligning the plate 96 with the recess 106.

It should also be pointed out, that a lock constructed in accordance with the invention may be quickly and easily changed, even by an unskilled person, for operation with a different key. The lock incorporates safety features such as the retaining member 86 which prevents inadvertent locking during the key changing process. Also, the lock incorporates relatively few additional parts beyond those which are normally used in a tumbler lock of the type described to afford the additional feature of being able to change the lock for operation with different keys.

It is understood that the foregoing embodiments are by way of example only and that many changes can be made thereto without departing from the spirit of the invention or from the scope of the annexed claims.

What I claim is:

1. A key operated lock comprising:

a body having a cylindrical bore therethrough and having at least one aperture communicating with said bore and extending radially outwardly from said bore into said body;

means forming a recess extending into said body adjacent said cylindrical bore;

an elongated plug extending axially in said cylindrical bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudinaly extending key slot therein for receiving a main key;

means in said lock forming a change key passageway in said plug, said change key passageway extending in substantially the same direction as said cylindrical bore and adapted for receiving a change key therein;

a plate pivotally mounted on said plug closing said change key passageway, said plate being constructed to be moved into said recess and open said passageway upon insertion of said change key when said plug is in a second rotational position relative to said body wherein said plate and recess are radially aligned;

tumbler means carried by said plug and movable radially in said cylindrical bore, said tumbler means registering with the apertures in said body in one rotational position of said plug relative to said body and adapted to engage the milled edge of a main key inserted in said key slot, said tumbler means including:

a plunger positioned for radial movement in said main key-following extensible means adjustably attached to said plunger for varying the dimension of said tumbler means as measured in a radial direction relative to said cylindrical bore, and

latch means releasably and adjustably securing said extensible means to said plunger to. prevent relative movement in a radial direction the-rebetween, said latch means extending into said changekey passageway for cooperation with a change key inserted into said change key passageway to release said extensible means from said plunger, whereby the extensible means cam move relative to said plunger to change the dimension of said tumbler means; and

a driver member movably disposed in each of said apertures in said body adapted to coact with said tumbler means to lock said plug against rotational movement in said bore when said plug is in said one rotation position relative to said body and when the main key is removed from said main key slot.

2. A key operated lock comprising:

a body having a cylindrical, bore therethrough and having at :least one aperture communicating with said bore and extending radially outwardly from said bore into said body;

an elongated plug extending axially into said bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudinally extending key slot therein for receiving a main key;

means in said lock forming a change key passageway extending in substantially the same direction as said cylindrical bore and adapted for receiving a change key therein, said elongated plug having a slot therein extending between said key slot and said change key passageway;

a change key retaining member slidingly positioned in said slot and projecting into said key slot and change key passageway, whereby said retaining member engages said change key to prevent the removal thereof when said key slot is empty;

a spring biasing said retaining member toward said key slot and said change key passageway;

tumbler means carried by said plug and movable radially in said cylindrical bore, said tumbler means registering with the apertures in said body in one rotational position of said plug relative to said body and adapted to engage the milled edge of a main key inserted in said key slot, said tumbler means including:

a plunger positioned for radial movement in said main key-following extensible means adjustably attached to said plunger for varying the dimension of said tumbler means as measured in a radial direction relative to said cylindrical bore, and

latch means releasably and adjustably securing said extensible means to said plunger to prevent relative movement in a radial direction therebetween, said latch means extending into said change key passageway for cooperation with a change key inserted into said change key passageway to release said extensible means from said plunger, whereby the extensible means can move relative to said plunger to change the dimension of said tumbler means; and

a driver member movably disposed in each of said apertures in said body adapted to coact with said tumbler means to lock said plug against rotational movement in said bore when said plug is in said one rotational position relative to said body and when the main key is removed from said main key slot.

3. A key operated lock comprising:

a body having a cylindrical bore therethrough and having a plurality of aligned apertures extending through one wall thereof into said bore;

means forming a recess extending into said body adjacent said cylindrical bore;

an elongated cylindrical plug extending longitudinally into said bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudinally extending key slot therein, a plurality of aligned apertures intersecting said key slot and adapted to register with the apertures in said body, and a longitudinally extending change key passageway intersecting the apertures in said plug;

a plate pivotally mounted on said plug closing said change key passageway, said plate being constructed to be moved into said recess and open said change key passageway upon insertion of said change key when said plug is in a rotational position relative to said body wherein said plate and recess are radially aligned;

a spring loaded driver disposed in each aperture in said body and adapted to enter the apertures in said plug when said apertures are in register to prevent relative rotation between said plug and body;

means cooperating wtih said body for retaining said drivers therein; and

tumbler means slidingly disposed in each aperture in said plug adapted to enter the apertures in said body when said apertures are aligned to prevent relative rotation between said plug and body and adapted to engage the milled edge of a key inserted in said key slot, said tumbler means including:

a key-following plunger having a hollow, cylindrical portion, a closed end portion, and a hollow projection extending radially therefrom,

extensible means having an upper portion slidingly disposed in said hollow, cylindrical portion and a lower portion adapted to engage the milled edge of said key, said upper portion having a plurality of circumferential flanges thereon, and

latch means including an elongated member having one end portion extending through said hollow projection into releasable engagement with the flanges on said upper portion, whereby said ex tensible means cannot move relative to said piunger, and having a second end portion extending into said change key passageway for cooperation with a change key inserted into said change key passageway to release said latch means whereby the extensible means can move relative to said plunger, and

10 a spring biasing such elongated member toward the upper portion of said extensible means.

4. A key operated lock comprising:

a body having a cylindrical bore therethrough and having a plurality of aligned apertures extending through one wall thereof into said bore;

an elongated cylindrical plug extending longitudinally into said bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudinally extending key slot therein, a plurality of aligned apertures intersecting said key slot and adapted to register with the apertures in said body, and a longitudinally extending change key passageway intersecting the apertures in said plug;

means forming a slot extending between said key slot and said change key passageway;

a change key retaining member slidingly positioned in said second mentioned slot and projecting into said key slot and change key passageway, whereby said retaining member engages said change key to prevent the removal thereof when said key slot is p y;

a spring biasing said retaining member toward said key slot and change key passageway;

a spring loaded driver disposed in each aperture in said body and adapted to enter the apertures in said plug when said apertures are in register to prevent relative rotation between said plug and body;

means cooperating with said body for retaining said drivers therein; and

tumbler means slidingly disposed in each aperture in said plug and adapted to enter the apertures in said body when said apertures are aligned to prevent relative rotation between said plug and body, and adapted to engage the milled edge of a key inserted in said key slot, said tumbler means including:

a key-following plunger having a hollow, cylindrical portion, a closed end portion, and a hollow projection extending radially therefrom,

extensible means having an upper portino slidingly disposed in said hollow, cylindrical portion and a lower portion adapted to engage the milled ed e of said key, said upper portion having a plurality of circumferential flanges thereon, and

latch means including an elongated member having one end portion extending through said hollow projection into releasable engagement with the flanges on said upper portion, whereby said extensible means cannot move relative to said plunger, and having a second end portion extending into said change key passageway for cooperation with a change key inserted into said change key passageway to release said latch means whereby the extensible means can move relative to said plunger, and

a spring biasing said elongated member toward the upper portion of said extensible means.

5. The key operated lock of claim 4 and also including:

means forming a recess extending into said body adjacent said cylindrical bore; and,

a plate pivotally mounted on said plug closing said change key passageway, said plate being constructed to be moved into said recess and open said change key passageway upon insertion of said change key when said plug is in a rotational position relative to said body wherein said plate and recess are radially aligned.

6. A key operated lock comprising:

a body having a cylindrical. bore therethrough and having a plurality of aligned apertures extending through one wall thereof into said bore;

an elongated cylindrical plug extending longitudinally into said bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudi nally extending key slot therein arranged to receive a main key and a master key, a plurality of aligned apertures intersecting said key slot and adapted to register with the apertures in said body, and a longitudinaliy extending change key passageway intersecting the apertures in said plug, said plug further including means forming a slot extending between said key slot and said change key passageway;

a change key retaining member slidingly positioned in said slot and projecting into said key slot and change key passageway, whereby said retaining member engages said change key to prevent the removal thereof when said key slot is empty;

a spring biasing said retaining member toward said key slot and change key passageway;

a spring loaded driver disposed in each aperture in said body and adapted to enter the apertures in said plug when said apertures are in register to prevent relative rotation between said plug and body;

means cooperating with said body for retaining said drivers therein; and

tumbler means slidingly positioned in each aperture in i said plug adapted to enter the apertures in said body when said apertures are aligned to prevent relative rotation between said plug and body and adapted to engage the milled edge of a key inserted in said key slot, said tumbler means including:

a plunger having a hollow, cylindrical portion, a

closed end portion, a master key lug depending therefrom and engageable with said master key, and a hollow projection extending radially from the side of said plunger opposite said master key lug,

extensible means having an upper portionsliding- 1y disposed in said hollow, cylindrical portion, and a lower portion adapted to engage the milled edge of said main key, said upper portion having a plurality of circumferential flanges thereon, and

latch means including an elongated member having one end portion extending through said hollow projection into releasable engagement with the flanges on said upper portion, whereby said extensible means cannot move relative to said plunger, and having a second end portion extending into said change key passageway for cooperation with a change key inserted into said change key passageway to release said latch means whereby the extensible means can move relative to said plunger, and a spring biasing said elongated member toward the upper portion of said extensible means. 7. A key operated lock compising: a body having a bore therethrough and having at least 12 one aperture communicating with said bore and extending radially outwardly from said bore into said body; an elongated plug extending axially in said bore and mounted in said bore for rotation about the axis thereof, said plug having a longitudinally extending key slot therein for receiving a main key, said key slot opening at one end of said elongated plug; means in said lock forming a longitudinally extending change key passageway which extends generally parallel to said cylindrical bore for receiving a change key therein, said key slot and change key passageway opening in the same end of said plug; means cooperating with said plug when it is rotated to a locking position within said body for preventing the insertion of a change key in said longitudinally extending change key passageway and movable to a position admitting said change key to the change key passageway when said plug is rotated in said body to a second position; tumbler means carried by said plug and movable radially in said cylindrical bore, said tumbler means registering with the apertures in said body in one rotational position of said plug relative to said body and adapted to engage a main key inserted in said key slot, said tumbler means including:

a plunger positioned for radial movement in said P s key following-extensible means adjustably attached to said plunger for varying the dimension of said tumbler means as measured in a radial direction relative to said cylindrical bore, and means reieasabiy and adjustably securing said extensible means to said plunger to prevent relative movement in a radial direction therebetween, said means releasably and adjustably securing said extensible means to said plunger extending into said change key passageway for cooperation with a change key inserted therein; and a driver member movably disposed in each of said apertures in said body and adapted to coact with said tumbler means to lock said plug against rotational movement in said body when said plug is in said one rotational position relative to said body and when the main key is removed from said main key slot.

References Cited by the Examiner UNiTED STATES PATENTS 1/1964 Great Britain.

MARVIN A. CHAMPION, Primary Examiner.

P. TEITELBAUM, Assistant Examiner. 

1. A KEY OPERATED LOCK COMPRISING: A BODY HAVING A CYLINDRICAL BORE THERETHROUGH AND HAVING AT LEAST ONE APERTURE COMMUNICATING WITH SAID BORE AND EXTENDING RADIALLY OUTWARDLY FROM SAID BORE INTO SAID BODY; MEANS FORMING A RECESS EXTENDING INTO SAID BODY ADJACENT SAID CYLINDRICAL BORE; AN ELONGATED PLUG EXTENDING AXIALLY IN SAID CYLINDRICAL BORE AND MOUNTED IN SAID BORE FOR ROTATION ABOUT THE AXIS THEREOF, SAID PLUG HAVING A LONGITUDINALLY EXTENDING KEY SLOT THEREIN FOR RECEIVING A MAIN KEY; MEANS IN SAID LOCK FORMING A CHANGE KEY PASSAGEWAY IN SAID PLUG, SAID CHANGE KEY PASSAGEWAY EXTENDING IN SUBSTANTIALLY THE SAME DIRECTION AS SAID CYLINDRICAL BORE AND ADAPTED FOR RECEIVING A CHANGE KEY THEREIN; A PLATE PIVOTALLY MOUNTED ON SAID PLUG CLOSING SAID CHANGE KEY PASSAGEWAY, SAID PLATE BEING CONSTRUCTED TO BE MOVED INTO SAID RECESS AND OPEN SAID PASSAGEWAY UPON INSERTION OF SAID CHANGE KEY WHEN SAID PLUG IS IN A SECOND ROTATIONAL POSITION RELATIVE TO SAID BODY WHEREIN SAID PLATE AND RECESS ARE RADIALLY ALIGNED; TUMBLER MEANS CARRIED BY SAID PLUG AND MOVABLE RADIALLY IN SAID CYLINDRICAL BORE, SAID TUMBLER MEANS REGISTERING WITH THE APERTURES IN SAID BODY IN ONE ROTATIONAL POSITION OF SAID PLUG RELATIVE TO SAID BODY AND ADAPTED TO ENGAGE THE MILLED EDGE OF A MAIN KEY INSERTED IN SAID KEY SLOT, SAID TUMBLER MEANS INCLUDING: A PLUNGER POSITIONED FOR RADIAL MOVEMENT IN SAID PLUG, MAIN KEY-FOLLOWING EXTENSIBLE MEANS ADJUSTABLY ATTACHED TO SAID PLUNGER FOR VARYING THE DIMENSION OF SAID TUMBLER MEANS AS MEASURED IN A RADIAL DIRECTION RELATIVE TO SAID CYLINDRICAL BORE, AND LATCH MEANS RELEASABLY AND ADJUSTABLY SECURING SAID EXTENSIBLE MEANS TO SAID PLUNGER TO PREVENT RELATIVE MOVEMENT IN A RADIAL DIRECTION THEREBETWEEN, SAID LATCH MEANS EXTENDING INTO SAID CHANGE KEY PASSAGEWAY FOR COOPERATION WITH A CHANGE KEY INSERTED INTO SAID CHANGE KEY PASSAGEWAY TO RELEASE SAID EXTENSIBLE MEANS FROM SAID PLUNGER, WHEREBY THE EXTENSIBLE MEANS CAM MOVE RELATIVE TO SAID PLUNGER TO CHANGE THE DIMENSION OF SAID TUMBLER MEANS; AND A DRIVER MEMBER MOVABLY DISPOSED IN EACH OF SAID APERTURES IN SAID BODY ADAPTED TO COACT WITH SAID TUMBLER MEANS TO LOCK SAID PLUG AGAINST ROTATIONAL MOVEMENT IN SAID BORE WHEN SAID PLUG IS IN SAID ONE ROTATION POSITION RELATIVE TO SAID BODY AND WHEN THE MAIN KEY IS REMOVED FROM SAID MAIN KEY SLOT. 